Festivalen blev planlagt fra 23 sep til 26 sep 2021 (3 dag(e)).
Firefly Music Festival finder sted i Dover, United Kingdom. Her er den fulde adresse på festivalen: The Woodlands of Dover International Speedway, Dover
Billie Eilish, The Killers, Tame Impala, Machine Gun Kelly, Lizzo, Girl In Red, Tate McRae, Glass Animals, Wiz Khalifa, Oliver Tree.
De mest populære genrer og undergenrer i den foregående udgave var:
electronic
hip hop
rock
indie
indie rock
alternative
electronica
electro
alternative rock
house
dance
experimental
indie pop
ambient
downtempo
psychedelic rock
trap
deep house
dubstep